A micro control unit (MCU) of a prior battery management system (BMS) does not recognize a small amount of a charging current supplied during operation in a sleep mode. In detail, after a battery pack reaches a constant voltage (CV) charging period, when a charger is connected thereto and a charging current is provided in a state where the MCU operates in a sleep mode, a small amount of the charging current is supplied, since the battery pack is in a full charged state. At this point, a limitation frequently occurs that the MCU of the BMS does not wake from the sleep mode, even if the charger is connected.
On the other hand, as a method for addressing the limitation that the MAC of the BMS does not wake up from the sleep mode, a method for configuring a separate circuit capable of recognizing whether a charger is connected, a method for modifying a circuit of a charger in order to generate and deliver a wake up signal for forcibly waking up the MCU of the BMS, and a method for making shorter a wake up period of a real time clock of the MCU of the BMS, etc., have been used. However, the method for configuring a separate circuit or the method for modifying the circuit of the charger becomes a reason for increasing a product manufacturing cost, and the method for making shorter the wake up period of the real time clock becomes a reason for increasing a consumption current of the battery pack and shortens the life of the product.
Accordingly, it is required to develop a technique capable of recognizing a connection of a charger and waking up an MCU without a circuit modification, when the charger is connected to a battery pack in a state where the battery pack of a BMS is fully charged and the MCU operates in a sleep mode.